{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38528","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T04:51:24.023Z","datePublished":"2025-08-16T11:12:21.667Z","dateUpdated":"2026-08-05T12:02:41.331Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:02:41.331Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject %p% format string in bprintf-like helpers\n\nstatic const char fmt[] = \"%p%\";\n    bpf_trace_printk(fmt, sizeof(fmt));\n\nThe above BPF program isn't rejected and causes a kernel warning at\nruntime:\n\n    Please remove unsupported %\\x00 in format string\n    WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0\n\nThis happens because bpf_bprintf_prepare skips over the second %,\ndetected as punctuation, while processing %p. This patch fixes it by\nnot skipping over punctuation. %\\x00 is then processed in the next\niteration and rejected."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The only trigger is a locally loaded eBPF program invoking a bprintf-like helper (`bpf_trace_printk`, `bpf_trace_vprintk`, `bpf_snprintf`, `bpf_seq_printf`) via the `bpf()` syscall; the format string is attacker-authored at `BPF_PROG_LOAD` time and consumed in the calling task's own context. No remote peer or packet can supply a format string.\nAC:L - The attacker fully controls the constant format string, so `\"%p%\"` deterministically reaches the `WARN_ONCE` in `format_decode()` and `\"%p%s\"` deterministically desyncs `bpf_bprintf_prepare()` from `bstr_printf()` on the first call — no race, no timing window, no dependence on memory layout the attacker cannot influence.\nPR:L - Reaching the helpers requires CAP_BPF plus CAP_PERFMON (or CAP_SYS_ADMIN) rather than full root, and these are routinely granted to non-root eBPF observability/profiling service accounts and can be delegated into a user namespace via a BPF token (supported in all affected 6.9+ branches), so a low-privilege non-root actor suffices.\nUI:N - The attacker performs self-contained `bpf(BPF_PROG_LOAD)` and program-run/attach operations; no victim must mount a filesystem, open a file, or take any other action.\nS:U - The faulty parse, the warning, and the stale-memory read all occur in the kernel's own security authority within the calling task's context; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The prepare/print desync makes `bstr_printf()`'s `FORMAT_STATE_STR` `strlen()` and copy uninitialized bytes from the per-CPU `bpf_bprintf_buffers` (512-byte `bin_args` followed by the 1024-byte `buf`, and potentially past the struct into adjacent per-CPU memory) straight into the `bpf_snprintf` output buffer or trace ring buffer that the attacker reads; because `nocopy_fmt` stores raw unhashed 64-bit values there, this leaks unsanitized kernel pointers, on top of the KASLR-defeating backtrace the `WARN_ONCE` dumps to dmesg.\nI:N - All writes stay bounded — `nocopy_fmt` checks `tmp_buf_end - tmp_buf` before storing, and `bstr_printf()`/`string()` gate every store on `str < end` — so the bug under-fills the argument buffer rather than overflowing it; no kernel or user memory is modified out of bounds.\nA:H - `\"%p%\"` triggers `WARN_ONCE` at `lib/vsprintf.c:2807`, which becomes a full kernel panic on the widely deployed `panic_on_warn=1` used in hardened cloud, Android, and fuzzing configurations — exactly the crash syzbot reported — and the unbounded `strlen()` over per-CPU memory can additionally fault; even without `panic_on_warn` the splat taints the kernel and can trip health-check tooling into taking the node down."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/helpers.c"],"versions":[{"version":"48cac3f4a96ddf08df8e53809ed066de0dc93915","lessThan":"97303e541e12f1fea97834ec64b98991e8775f39","status":"affected","versionType":"git"},{"version":"48cac3f4a96ddf08df8e53809ed066de0dc93915","lessThan":"61d5fa45ed13e42af14c7e959baba9908b8ee6d4","status":"affected","versionType":"git"},{"version":"48cac3f4a96ddf08df8e53809ed066de0dc93915","lessThan":"e7be679124bae8cf4fa6e40d7e1661baddfb3289","status":"affected","versionType":"git"},{"version":"48cac3f4a96ddf08df8e53809ed066de0dc93915","lessThan":"6952aeace93f8c9ea01849efecac24dd3152c9c9","status":"affected","versionType":"git"},{"version":"48cac3f4a96ddf08df8e53809ed066de0dc93915","lessThan":"1c5f5fd47bbda17cb885fe6f03730702cd53d3f8","status":"affected","versionType":"git"},{"version":"48cac3f4a96ddf08df8e53809ed066de0dc93915","lessThan":"f8242745871f81a3ac37f9f51853d12854fd0b58","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/helpers.c"],"versions":[{"version":"5.13","status":"affected"},{"version":"0","lessThan":"5.13","status":"unaffected","versionType":"semver"},{"version":"5.15.190","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.147","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.100","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.40","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.15.8","lessThanOrEqual":"6.15.*","status":"unaffected","versionType":"semver"},{"version":"6.16","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"5.15.190"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.1.147"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.6.100"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.12.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.15.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.16"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/97303e541e12f1fea97834ec64b98991e8775f39"},{"url":"https://git.kernel.org/stable/c/61d5fa45ed13e42af14c7e959baba9908b8ee6d4"},{"url":"https://git.kernel.org/stable/c/e7be679124bae8cf4fa6e40d7e1661baddfb3289"},{"url":"https://git.kernel.org/stable/c/6952aeace93f8c9ea01849efecac24dd3152c9c9"},{"url":"https://git.kernel.org/stable/c/1c5f5fd47bbda17cb885fe6f03730702cd53d3f8"},{"url":"https://git.kernel.org/stable/c/f8242745871f81a3ac37f9f51853d12854fd0b58"}],"title":"bpf: Reject %p% format string in bprintf-like helpers","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2025-11-03T17:39:24.864Z"}}]}}